Method and apparatus for lining container closures



W. J. TIMSON Jan. 22, 1963 METHOD AND APPARATUS FOR LINING CONTAINERCLOSURES Filed Dec. 50, 1959 /olo W i;

y f n www da 0 l lgmlllw United States Patent Utilice 3,074,810 PatentedJan. 22, 1953 3,074,810 METHOD AND APPARATUS FR LHNENG CONTAINERCLOSURES William J. Timson, Arlington, Mass., assigner to W. R.

Graee 8L Co., Cambridge, Mass., a corporation of Connecticut Filed Dec.30, 1959, Ser. No. 862,030 4 Claims. (Cl. 117-43) This invention isconcerned with the application of sealing compound to container closuresand particularly to that method which is known as die lining.

In the container industry, the gasket which is placed on the closures toseal the mating parts, such as can end and can body is known as a liningLinings are usually applied to container closures as liquid compositions which are subsequently dried or in other ways consolidated into asolid mass. These compositions are known both as sealing compounds andlining cornpounds. There are two general methods of lining compoundapplication. That which is used almost universally in the lining of foodcan closures consists in rotating a closure beneath a nozzle from whicha measured quantity of compound is ejected onto the closure as it isrotating. Consequently, a peripheral stripe of compound is laid on thejoint area. This is subsequently dried if the suspending fluid be wateror a solvent or it is jelled if the compound is in the nature of aplastisol. Lining by the rotary method is a very fast procedure.

The other process, die lining is essentially a printing operation. Adie, shaped to conform to the sealing periphery of the closure, is rstcoated with lining compound then pressed into contact with the closure.Since the closure need not rotate, die lining makes it possible to lineends having odd shapes. The rectangular end used for the common sardinecan is a typical example of an odd shaped end.

However, die lining is slow because it is necessary rst to coat the dieand then move the coated die into contact with the closure. The machineoutput of a die lining machine seldom exceeds one hundred and fiftyclosures a minute. For comparison, the output of rotary machines iscommonly about 350 closures a minute. Slowness is due not only to thetime required to translate the die from pickup to printing positions buttime limitations are also imposed by the nature of the compounds thatmust be used in die lining.

Die lining requires that lthe lining compound possess contradictoryproperties. When the die enters the pan of compound, the Compound muststick to the die. When the die is lowered onto the closure, the compoundmust leave the die and stick to the closure. The cornpound cannot bestringy or sticky, for it must break away cleanly, smoothly anduniformly when the die is lifted to assure that the amount of compounddeposited on each closure remains uniform throughout the closure run. Asin all cases where properties must conllict, the operative result is acompromise. Those compromises which are necessary in formulationseverely restrict the compounder in his choice of materials and limitthe range of lining characteristics that he may give to the lining,

There have been various attempts to speed up the mechanical operationand eliminate some of the contradictory requirements in compounding byfeeding the die with compound led to its printing face through internalpassageways. For example, it has been proposed to provide a die withsome thirty small needle valves placed around the periphery of the die.The valves were arranged to open when the die contacted the closure andto discharge compound onto the closure through orifices beneath eachvalve. This proposal is not satisfactory because since all sealingcompounds contain suspensoids, bits of coagulum or agglomerates so alterthe relative discharge rate of each valve that the individual nozzlesdeliver unequal quantities of compound after a very few minutes ofoperation under commercial conditions. It is my experience that othersuggested internally fed dies have not produced satisfactory resultsbecause the distribution of compound on the printing surface of the diedoes not remain constant and, consequently, the cross-section of thedeposited gasket varies around the periphery of the closure.

The objects of this invention are to achieve linings of uniformcross-section and to produce a lining die on which the distribution ofcompound on its closure contacting surface will be uniform. An equallyimportant object is to produce Ia `die which will deliver compound tothe closure rapidly and uniformly. An auX- iliary object is to produce adie which may be used as an accessory on rotary machines and thusproduce dielined ends with the rapidity which characterizes the rotaryapparatus. The single ligure is a Vertical crosssection through myimproved die.

l have found that if the compound which is fed to the printing tip isforced through a long and exceedingly narrow passage in which lthepressure drop is at least approximately two orders of magnitude higherthan the pressure drop which exists around the header feeding thepassageway, the amount of compound moving out `of the exit and onto theprinting tip is substantially, peripherally uniform; and further, if thepassageway is sufficiently narrow, compound will not flow out of itunless it is impelled by pressure in the header passage. The dimensionsof the narrow passageway which are necessary to achieve these resultsare a function of the viscosity of the compound. lf that viscosity ishigh, for instance, about 20,000 centipoises at 6 r.p.m. and 8500centipoises at 60 rpm. as measured on a Brookfield viscometer using a #4spindle, the gap width may tbe 0.025 inch. If the gap width is reducedto 0.015 inch, then quite conventional compounds with their much lowerviscosities will run satisfactorily.

The ratio of length of passageway to its width also is a function ofviscosity. lt may be 40 to 1 in the case of high viscosity material andto l when the viscosity is substantially lower.

Further, if the required amount of compound is allowed to bloom onto thedie face by opening the needle valve while the die is out of Contactwith the closure, compound iiow can take place during a period whichexceeds 50% of the machine cycle. The bloomed material can then bedetached from the die and caused to adhere to the closure yby a veryquick contacting die stroke which needs to last but a few milliseconds.

The assembly which may be called a nozzle has as main elements a jacket10 and a liner 11. Their coniignration is that of the gasket to beapplied and hence the die assembly may be square, round, or even followthe exotic shape of some novelty package. The liner 11 is retainedlongitudinally in jacket l0 by its shoulder 12 which is seated in arecess or counterbore 13 cut in the top face 14 of jacket 10. The upperface 15 of shoulder l2 is engaged by a retainer plate 16 held in`position by the cap screws 17. The liner 11 is centered by the shortcentering shoulder 18, the dimensions of which are such as to form aclose t within the interior walls 19 of the jacket 10. Below shoulder 18the exterior wall 21 of liner 11 does not contact the jacket but isspaced from the interior wall 19 of jacket 10 a minute distance, forexample, about 0.015 inch. The lower extremities both of jacket 10 andliner 11 narrow into tip portions 22 and 23 respectively and togetherform the printing tip 24 of the die. The exterior walls of tip portions2?. andy 23 extend upwardly and outwardly away from the interior marginsas shown at Sii. yThe passageway 25 which is thus formed between jacketl@ and liner l1 is completely unobstructed save for three or four smallcentering pins 26 which project from the wall 2l of the liner and engagethe wall l) of the jacket.

ITowards its upper end, jacket lll swells out into a large peripheralboss 27 which covers a large, open-faced channet 23, surrounding liner11. A port 29, is formed at one point in the boss 27, into which pipenipple 3l is tapped. Nipple 3l, together with elbow 32', and valveconnector 33, form an entrance conduit for compound which is admittedinto the die through the needle valve 34. Preferably this valve isidentical to those developed for use on rotary lining machines and maybe operated either by a mechanical linkage or electromagnetically. Sincethis element is well known and has achieved a. separate status in theart (for example, see U.S. Patent Number 2,442,179) it will not befurther described. All such valves operate in timed relation -to themovement of the closure through a lining 'machine and all serve todeliver a predetermined and uniform amount of compound to the closureduring their operating cycle. Following conventional practice, compoundis supplied to the valve from a tank equipped with a pneumatic inlet andpressure adjusting valve to provide an adjustable pneumatic headpressure. In this instance a head pressure is chosen which will forcethe proper amount of compound -to accumulate ou the tip. Of course, thepressure must be varied `toviaccord Iwith the viscosity of theparticular compound which is used.

There is a large free air passage through the liner lll. Always, theliner, whatever its peripheral configuration, is tubular and has openends. Were these ends closed, air trapped under the die as i-t descendson the closure would blow the lining out of place.

The Ilinear extent of the gap between the lower wall 3S, of channel 2dand the extremity 24- of the tip is quite long. lts optimum lengthdepends upon the characteristics of tie compound, but, as an example, ifthe gap 25 is 171.000 ot an inch wide, the linear dimension of the gapbetween the `lower wall of channel 2:8 and the extremity 24 isapproximately an inch and a half. The volumetric capacity of the channelor compound header 28 should be large. Preferably, in order to minimizepressure uctuations, it should be ten times or more the Volumetric:capacity of the gap 25 between channel 23 and ti-p 24.

The ettect of this design is to impose a high resistance to the flow ofcompound in the exit passage and consequently to mantain a veryconsiderable back pressure on the compound occupying channel 28. As aresult of the high back pressure, the pressure exerted all around theperiphery is quite uniform and a uniform ow of compound moves ldown theexit passageway 2S. Spotty or streaky delivery is eliminated.

The use of these nozzles on a conventional slide type lining machineIwill now be described. Such machines `.ave been known for years.

Essentially these machines consist `of a chuck which is cyclicly liftedand lowered by a cam. The chuck is lo-aded and unloaded by a slide whichreciprocates horizontally lacross the working `face of the machine.Unlined closures fare stacked at one end. In its retreating stroke, theslide passes beneath the stack of closures. On its advance, knives onthe slide cut the lowermost closure from the stack and place the closureon the chuck. Meanwhile, the `forward end oi" the slide has engaged theclosure previously resting on the chuck and carried it forward to tuckit beneath a stack of lined closures which piles up at the opposite endof the machine. Such machines are equipped with cams having very wideadjustability which may operate a mechanical linkage connected to theneedle valve of the compound nozzle, but more frequently today open andclose an electrical breaker which l controls the electric circuitA of`an electro pneumatic needle Valve opening and closing device.

The die or" this invention is substituted for the conventional electropneumatic needle nozzle. A chuck designed to receive, for example, aclosure or end of a sardine can is substituted for the round chuck. Themiter gearing which causes the chuck to rotate continuously is disabled.The height of the die is so adjusted that, when lthe chuck lifts, theend just contacts the tip of the die. The timing cam is adjusted to openand close the needle valve `while 'the die is out of contact with theclosure and the lift of the needle valve is adjusted to cause thedelivery of tue `desire-d amount of sealing compound to the die duringthe time that the needle valve is open. When the chuck rises and bringsthe closure into contact with the tip of the die and then drops, theclosure falls away, bearing with it compound which has been exuded onthe tip of the die during the out-of-contaot period.

Since it is not necessary to design la compound which will `stick to thedie when it is dipped into the mass, a much wider range of compounds canbe used. Webby or stringy compounds can be completely avoided. Compoundswhich possess quick, sharp break characteristics can be used. IFurther,because the compound does not iiow into the tip as it is being`deposited on the end (a requirement in prior dies) contact time can -bevery short, and need `by only the time required to permit the chucklifting cam to lift `and lower the chuck smoothly, la matter of twentymilliseconds. The compound may gather on the tip during the wholeout-of-contact cycle, but practically labout 40 milliseconds are`allowed for the compound gathering cycle. Consequently, this die liningoperation is very fast. The machine out-put reaches about twice tha-t ofconventional die lining machinery. The quality of the lining is alsoimproved. It is more uniform and holds a better cross-section.

I claim:

l. An internally `fed `lining die adapted for use in combination withdie lining machinery comprising a body having `a terminal printing tipshaped to conform to the sealing periphery of the container closure towhich the lining is to be applied, a straight, parallel-walledpassageway having a closed upper end interiorly located in the tbody andhaving a uniform spacing between its walls not exceeding 0.025 inch, thepassage ending in a continuous opening in the extremity of said tip, achannel having its open -ace `directed towards the interior wall formedin the exterior wall of the passage and normal to said passage, formingthereby a compound header having a volumetric capacity of not less thanten times that of the volume of the passage between the channel and thetip opening, the zone of discharge from the channel in-to the passagebeing located at a idistance from the tip opening of not less than 40Itimes the width of the passage,

' air vent comprising an open bore extending longitudinally through thebody and occupying =a major portion of the cross-sectional area enclosedby said passage, a port to admit compound into the channel, a conduitconnected to the port, and a valve in the conduit adapted to be openedLand closed in timed relation to the movement of closure-s through themachine.

2. That method of forming lining elements on container closures whichcomprises providing an internally fed die having a printing tip havingas its contour the desired shape or' the lining element and providedwith a continuous peripheral slot communicating with a likeshapedcompound feed passage, applying pressure to lining compound supplied tosaid passage only when the tip is out of contact with a container topermit the buildup on said tip of a pendant exudation of compound allparts of which are uniform in cross-section, cutting ofi the pressurewhen the pendant compound reaches a preselected volume, thenprinting-oil the exudation by bringing an unlined closure into momentarycontact with said printing tip while preventing the displacement of thedeposted compound by venting the air in the area enclosed by saidcompound through a central air vent, removing the closure, and repeatingthe succession of operations `on successive unlined closures.

3. An internally fed lining die adapted for use in combination with dielining machinery comprising a tubular jacket having a straight walledbore the crosssection of which conforms to the shape and size of thelining to be imprinted on a container closure, a horizontal channelformed in the jacket surrounding the bore and having its open facedirected towards the bore, `a tubular liner the exterior walls of whichenclose a shape geometrically :similar to that of the bore maintained inspaced relation to the walls of said bore by aligning means adjacent theupper end of the jacket to form a straight, parallel Walled passage of auniform width not exceeding 0.025 inch, the Walls of the passage deninga continuous opening in said tip, said tip being located not less than40 times the width of the passage below the channel, the walls of thechannel together together with the liner forming a compound headerhaving a volumetric capacity not less than ten times that of the passagebelow said channel, the bore of the liner occupying a major portion ofthe cross-sectional area of said liner and forming an unobstructed airpassage open to the atmosphere at its upper end, the walls of both thejacket and the liner at said printing tip leading abruptly upward andoutwardly from the margin of the passage to permit contact with theclosure at said tip only at the margin of the passage, a port leadinginto the channel, a conduit connected to the port, and a valve in theconduit adapted to be opened and closed in timed relation to the motionof closures through the machine.

4. AAn internally fed lining die in accordance with claim l wherein thepressure drop in the passage leading from the compound header to theprinting tip is at least two orders of magnitude `higher than thepressure drop around the channel forming the header.

References Cited in the tile of this patent UNITED STATES PATENTS2,286,978 Rivera .lune 16, 1942 2,859,476 Lainson Nov. ll, 19582,888,366 Barsky et al May 26, 1959l

2. THAT METHOD OF FORMING LINING ELEMENTS ON CONTAINER CLOSURES WHICHCOMPRISES PROVIDING AN INTERNALLY FED DIE HAVING A PRINTING TIP HAVINGAS ITS CONTOUR THE DESIRED SHAPE OF THE LINING ELEMENT AND PROVIDED WITHA CONTINUOUS PERIPHERAL SLOT COMMUNICATING WITH A LIKESHAPED COMPOUNDFEED PASSAGE, APPLYING PRESSURE TO LINING COMPOUND SUPPLIED TO SAIDPASSAGE ONLY WHEN THE TIP IS OUT OF CONTACT WITH A CONTAINER TO PERMITTHE BUILDUP TO ON SAID TIP OF A PENDANT EXUDATION OF COMPOUND ALL PARTSOF WHICH ARE UNIFORM IN CROSS-SECTION, CUTTING OFF